function Person(firstname, lastname, age, cons) {
    this.firstname = firstname;
    this.lastname = lastname;
    this.age = age;
    this.cons = function() {
        console.log(1 + 2);
    }
}
var p = new Person("ma", "hu", 23);
Person.prototype.name = function() {
    return this.firstname + " " + this.lastname;
}
console.log(p.name())

var girl = new Person("zou", "yuxin", 22);
console.log(girl.name())

console.log(p.name === girl.name)

console.log(p.__proto__ === Person.prototype)

function Person2(name, age) {
    this.name = name;
    this.age = age;
}
var boy = new Person2("mahu", 23);

p.cons.call(boy)

console.log(Person2.arguments)
console.log(Person2.caller)
console.log(Person2.length)
console.log(Person2.name)
console.log(Person2.prototype)



function A() {
    this.firstname = "mahu";

}

function B() {
    this.age = 23;
    A.call(this);
}

function C() {
    B.call(this);
    this.country = "CHINA";
}

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